Steam generator for portable plants



March 1 1927. w. HOJER swam GENERATOR FOR PORTABLE PLANTS -Fi1ed Nov. 6. 1926 WILHELIVI I-IOJER, OF MUNICH, GERMANY, ASSIGNOR TO SIEMENS-SCHUCKERTWERKE GESELLSCHAFT MIT IBESCHRANKTER HAFTUNG, 0F SIEMENSSTADT, NEAR IBER- LIN, GERMANY, A CORPORATION OF GERMANY.

STEAM GENERATOR FOR PORTABLE PLANTS.

Application filed November 6, 1926, Serial No. 146,803, and in Germany July 15, 1925.

My invention relates to a Benson steam generator, such as that disclosed in British Patent No. 206,559, complete accepted date Nov. 15th, 1923, for portable plants, more particularly for locomotives.

In the generation of steam of very high pressure in steam generators of standard design it is extremely difiicult to obtain steam perfectly free from water. By the ebulhtion of the water at the surface in the customary drums of steam boilers water is carried along by the steam. It is very difiieult to separate this water from the steam. The water in the steam has the effect of reducing the superheating temperature.

According to the proposal of Benson this drawback is eliminated by bringing the water in a system of pipes up to or above the critical pressure by means of a feed pump and heating it independent thereof up to or above the critical temperature. At the critical values the water passes directly into steam i. e. without the ebullition phenomena appearing at lower pressures. The pressure of the steam is then, prior to the entrance into the power engine, reduced to the operating pressure, the desired superheating being obtained by the further supply of heat.

The carrying out of this process is comparatively simple in stationary plants since electric current is available for driving the feed pump which at the same time serves to maintain the critical pressure in the steam generator independent of the supply of heat, so that the starting of the steam generator offers no difficulties whatever.

In portable plants, such as portable engines and locomotives, the conditions are less favorable, while, on the other hand, the Benson steam generator is particularly suitable for them because it combines small space requirement with high output capacity. The provision of a motor-generator with storage battery, for instance, increases the weight of the locomotive considerably,

and makes large demands in regard to at tendance. The provision of an internal combustion engine for driving the feed pump appears likewise objectionable in view of the attendance required and the necessity of carrying a special supply of liquid fuel.

My invention provides an extraordinarily reliable and simply handled arrangement for starting the engine which has the further advantage that it is very economical. My iii-- yention consists substantially in providing in COIIJLIIlCtlOIl with the steam generator an auxiliary boiler which serves for operating the feed water pump driven by a. steam engine, preferably a steam turbine with high and low pressure stage. This auxiliary steam generator may consist of a separate small steam boiler provided with an oil furnace, for instance. The feed heater may, however, equally well be employed provided it is so designed as to adapt it to the generation of steam in the manner of a flue gas or fire-tube boiler. The feed heater requires no special furnace. Before the englue is started the feed water heater is charged from a separate steam boiler in the manner of the fire-less locomotive. During the service sufiicient heat is applied to it partly by the flue gases, partly by the exhaust steam, in order to maintain an ample stock of steam of sufficiently high pressure for starting.

The steam from the auxiliary boiler is first fed to the low pressure stage of the driving engine for the feed water pump so that the pump starts and puts the main boiler under pressure, the furnace of which, preferably an oil or pulverized coal furnace, is started simultaneously. On account of the small content of water the steam generator quickly attains the critical temperature of about 374 and is now able to supply steam to the high pressure stage of the engine driving the pump. The pump now attains its-full output and is able to supply to the steam generator the quantity of feed water necessary for driving the locomotive so that the locomotive is now ready to start.

I shall now proceed to describe the arrangement and function of the steam generator according to my invention with reference to the embodiment illustrated by way of example in the drawing affixed hereto.

Referring to the single figure of the drawing it will be seen that the steam gen erator 1 consists substantially of a system of pipes composed of two sections, the heater proper 2 and the superheater 3. Between both is located the throttle valve 4 which reduces the pressure of the steam from the critical pressure of approximately 225 atmospheres to the service pressure of approximately 100 atmospheres. The steam generator is fed by the pump 5 which is driven by a steam turbine 6 having a highpressure stage 7 and a low-pressure stage 8. The highand the low-pressure stages of the turbine may be supplied with steam each separately or both in series. The low-pressure stage 8 is fed from the auxiliary boiler 9 which is equipped with a separate furnace 10. This auxiliary boiler is preferably mounted on the engine itself and below the main steam generator. This has the advantage that on the one hand the main and auxiliary furnace are located closely together and may be attended to form the same stand and on the other hand that the steam pipes are short and can be more easily accommodated and kept tight than if the auxiliary boiler were located on the tender. The waste gases of the auxiliary boiler 9 are discharged into the atmosphere together with the waste gases from the main boiler through the feed heater 11 and the stack 12. As already stated this feed heater may also serve as auxiliary boiler. Between the high-pressure cylinder 13 and the low-pressure cylinder 14 is located the intermediate superheater 15 heated by the waste gases which superheater at the same times serves as receiver.

The starting of the engine is effected in the following manner: The auxiliary boiler 9 is fired or the feed heater charged with steam. The available steam is then passed through pipes 16 and 17 into the low-pressure stage 8 of the driving turbine 6. The turbine starts and generates the prescribed pressure in the heater 2. Simultaneously the main furnace 18 is started and the quickly forming steam of critical pressure and critical temperature is reduced down to the operating pressure in the throttle or reducing valve 4 and is then passed through the superheater 3 first to the high-pressure stage 7 of the driving engine for the pump and after leaving this part the steam is finally reduced in pressure in the low-pressure stage 8 of the engine. The low-pressure steam supply from the auxiliary boiler is then stopped. The pump is now able to develop its full capacity and the steam generator 2 becomes enabled to supply the quantity of steam necessary for driving the 10- comotive.

The steam flows now from the super.- heater 3 into the high-pressure cylinder 13, thence through the pipe 19 into the intermediate superheater 15 and from this superheater, which at the same time serves as receiver into the low-pressure cylinder 14. The exhaust steam emanating from the latter serves for producing artificial draft in the manner customary in locomotives; at

iueiaevi the same time, as is customary, it serves for conveying the feed water from the tender- (not shown) into the feed heater 11.

My invention thus ofiers the possibility of employing the Benson process not only I on vehicles, but also on vessels, in a simple, reliable and economical manner.

Various changes and modifications in the details of my invention may be made within the scope of my claims without departing from the spirit of my invention.

I claim as my invention 1. In a portable high-pressure high-temperature boiler plant operating on the Benson principle, means for starting and maintaining the operation of the boiler, comprising a main steam generator for producing high temperature steam at high pressure, a feed pump for furnishing water to said generator at the high pressure required, a prime mover for operating said pump and being suitably connected to said main generator to receive steam therefrom during the normal boiler operation, and an auxiliary boiler operable independently of said main generator for furnishing steam to said prime mover of sufficient pressure to start said pump for generating the feed water pressure in the main generator necessary tostart its operation.

2. In a portable high-pressure hightemperature boiler plant operating on the Benson principle means for starting and maintaining the operation of the boiler, comprising a main steam generator for producing high temperature steam at high pressure, a feed pump for furnishing water to said generator at the high pressure required, a rime mover for operating said porn and eing suitably connected to said main generator to receive steam therefrom during the normal boiler operation, and an auxiliary boiler operable independently of said main generator but mounted directly below said main generator, for furnishing steam to said prime mover of suflicient pressure to start said pump for generating the feed water pressure in the main generator necessary to start its operation.

3. In a portable high-pressure high-temperature boiler plant operating on the Ben son principle means for starting and maintaining the operation of the boiler, comprising a main steam generator for producing high temperature steam at high pressure, a feed pump for furnishing water to said generator at the high pressure required, a prime mover for operating said pump and being suitably connected to said main generator to receive steam therefrom durin the normal boiler operation, and an auxiliary boiler operable independently of said main generator but mounted directly below said main generator for furnishing steam to said prime mover of sufficient pressure to start said meiaerr pump for generating the feed water pressure in the main generator necessary to start its operation and a feed Water heater and means for conducting the flue gases of the main generator and of said auxiliary boiler through said feed Water heater.

4:. In a portable high-pressure high-temperature boiler plant operating on the Benson principle, means for starting and maintaining the operation of the boiler, comprising a main steam generator for producing high temperature steam at high pressure, a feed pump for furnishing Water to said generator at the high pressure required,

a two stage expansion steam engine for operating said pump, having its high pressure stage connected to said main generator to receive steam therefrom during the normal boiler operation, and an auxiliary boiler operable independently of said main generator for furnishing steam to the low pressure stage only of said steam engine to start said pump for generating the feed Water pressure in the main generator necessary to start its operation.

In testimony whereof affix my signature.

WILHELM HOJER. 

